A project of Google-parent Alphabet has filed a suit against Uber, after a botched email exchange revealed "striking resemblance" between the companies' self-driving car designs.

Engineers at Google's self-driving car company, Waymo, were "apparently inadvertently" copied on an email from a company providing components for Uber's self-driving car project that allegedly revealed drawings of Uber's technology, according to a lawsuit filed in San Francisco court on Thursday.

The drawings of the 3-D sensors contained Alphabet's trade secrets, the lawsuit claims. The suit also alleges that a former Google employee "downloaded more than 14,000 highly confidential and proprietary files shortly before his resignation."

The engineer, Anthony Levandowski, took "extraordinary efforts to raid Waymo's design server and then conceal his activities," the suit alleges. Levandowski left Google to launch a self-driving truck company called Otto, which went own to be acquired by Uber.

"We take the allegations made against Otto and Uber employees seriously and we will review this matter carefully," an Uber spokeswoman told CNBC.